Abstract
Abstract: :
Purpose: TULP1, a member of a family of four proteins with unknown function designated tubby-like proteins or TULPs, is expressed specifically in the inner segments and connecting cilium of photoreceptor cells. Mutations in TULP1 are associated with autosomal recessive retinitis pigmentosa and Tulp1 knockout mice develop an early-onset, progressive photoreceptor degeneration involving both rods and cones. To explore the physiologic function of TULP1, we are pursuing the identification of interacting proteins. Methods: Immunoprecipitation experiments were performed with bovine retinal homogenates and a polyclonal anti-TULP1 antibody. Immunoprecipitation products were seperated by SDS-PAGE, protein bands excised, digested in situ with trypsin and identified by LC MS/MS. Results: The following proteins were immunoprecipitated: Microtubule Associated Protein 1B, Clathrin Heavy Chain, Interphotoreceptor Retinoid Binding Protein, Dynamin-1, Rab Gerynl Gerynl Transferase, Dynein Intermediate Chain, Tubulin and Actin. In vitro pull-down experiments and in vivo co-immunoprecipitation experiments are in progress to further evaluate these possible TULP1 interactions. Conclusions: Several of the identified proteins are involved in various aspects of vesicle transport or protein movement. TULP1 may function in intracellular trafficking of proteins synthesized in the inner segment to the outer segment of photoreceptor cells. These results provide a first step toward defining the mechanism underlying photoreceptor degeneration caused by mutations in TULP1.
Keywords: protein structure/function • photoreceptors • retinal degenerations: cell biology